Why is my butt so itchy?


We know that you secretly come to Retroflexions to read about all the most embarrassing topics in gastroenterology, so we are pleased to announce that this entire post will be devoted to the all-important topic of pruritis ani! For those of you who don’t know, pruritis ani (proo-rí-tus a-ní) is the medical term for having an itchy butthole (I will respect your modesty and refer to this instead as an itchy anus for the rest of this article). Now I don’t mean the casual itch that is easy to scratch and occasionally part of normal life: Pruritis ani implies that the itching is so bad that you feel the need to furiously scratch, and then scratch some more. The itch is almost a type of pain, and it makes you want to scratch until the skin peels off just to temporarily relieve the itch!

Pruritis ani is a very common problem, but probably underappreciated since most patients with this condition do not seek out medical care. However, a bad case of itch anus can ruin one’s day (or week) and the cause of the itch can often remain a mystery. However, you should fear not: We will cover some of the common sources of pruritis ani, in an effort to protect you from this itchy ailment!

As you will soon learn, the simple tomato is a common source of pruritus ani!

There are several medical conditions that can cause the dreaded itchy anus. These conditions include hemorrhoids, anal fissures, frequent diarrhea, certain skin conditions, parasites, infections, anal cancer, and several other problems. So if you have a case of the itch you just can’t quite scratch, and it lasts for more than two weeks or so, it’s a good idea to go see a doctor to make sure nothing serious is going on back there.

Creams, soaps, baby wipes, and other products can also cause intractable anal itching. This can be a direct allergic-type reaction to the product itself, or in the case of soap and wipes, a side-effect of washing away the body’s natural skin oils and causing skin breakdown. This makes the skin back there susceptible to the damaging effects of excess moisture, resembling dishpan hands (only in this case the condition would probably be called “dishpan anus”).

Very commonly, anal itch is brought on by something that we are eating and drinking. The skin of the anus comes into contact with almost everything that we put in our bodies, by direct contact with stool. Several of the most common offending substances are listed below. Usually cutting back on some of these foods/drinks can stop the itch:

  • Coffee (including decaffeinated coffee)
  • Chocolate
  • Alcohol (especially beer and wine, less commonly liquor)
  • Spicy foods
  • Citrus
  • Tomatoes
  • Soft drinks/soda
  • Dairy

At this point, you might be wondering what precipitated this wonderful article. Why would I choose to write about this topic and not some other, possibly more interesting topic? Well in the interest of full disclosure, I recently suffered from a particularly aggressive episode of pruritis ani and was having trouble coming up with the cause. I reviewed my diet for any obvious suspects but remained puzzled…I wasn’t eating any more of the commonly offending foods than usual, and otherwise felt fine. Well, I started thinking about everything I ate or drank in the few days before the itching started and the possible culprit food became apparent. All it took was a quick Google search to confirm my theory. The offending food was loosely related to poison ivy, and I was eating large quantities of it for the few days before the itching started as we just bought a big container of these delicious little things…can you guess what I’m referring to?

Salted and roasted cashew nuts. The natural appearance of the cashew fruit before harvesting is the featured image for this post, and looks kind of like a cashew nut shoved into the rear-end of a tiny apple…probably nature’s way of warning us not to eat these things!

Let it be known that cashews, especially while eaten by the fistful from a giant family-size container, can cause a furious case of the itchy anus! Apparently, the outer shells of the cashew contain substances called anacardic acids, which are the exact same irritants found in poison ivy! According to Wikipedia, if the cashew is roasted properly, the toxin is deactivated…so I suspect that the giant container of cashews was so cheap because they probably skipped that proper roasting step for the sake of mass production. If you’ve ever had a bad case of poison ivy, try imagining that feeling affecting your anus instead of your arms or legs…yikes! So needless to say, no more cashews for me…or at least not in any large amount.

Poison Ivy: Probably not a wise idea to use this as toilet paper either!

Until next time…keep scratching!

For a nice review of the topic of pruritis ani, see Ansari, P. Pruritis Ani. Clin Colon Rectal Surg 2016;29:38-42.

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